According to Ačaṙyan, borrowed from a “Caucasian” (Kartvelian?) root of the form *cux(“soot; smoke; darkness”) whence also Georgian წუხვა(c̣uxva, “sadness, sorrow”), figuratively, as if a “smoke of heart”, with a sense development seen also in Persian دود‎(dud, “smoke; sorrow”); and მწუხრი(mc̣uxri, “dusk”).